Generally, a cathode ray tube is formed with a vacuum vessel where a panel, a funnel and a neck are sealed to each other in a body. A phosphor film is formed on the inner surface of the panel, and an electron gun is mounted within the neck. A mask assembly is internally fitted to the panel and a deflection unit is externally mounted around the funnel.
With the above-structured cathode ray tube, the electron beams emitted from the electron gun are deflected by the deflection unit, and scanned toward the phosphor film. The electron beams pass through the mask holes of the mask assembly, and collide against the phosphor film formed on the inner surface of the panel, thereby emitting light and displaying the desired image.
With the conventional cathode ray tube, the maximum deflection angle of the electron beams is established to be in the range of 102˜106°. In order to correctly land the electron beams on the relevant areas of the phosphor film within the range of the maximum deflection angle, the electron gun should be spaced apart from the phosphor film with a distance sufficiently large to deflect the electron beams.
Accordingly, the conventional cathode ray tube has a large tube thickness and a large volume, accompanying with the disadvantages related thereto.
Recently, the deflection of the electron beams has been wide-angled (the maximum deflection angle being about 125°) to slim the cathode ray tube, and in this case, the thickness of the panel and the funnel should be enlarged to achieve a reasonable explosion resistance characteristic.
However, in order to enlarge the thickness of the panel and the funnel while maintaining the conventional external dimension thereof, the internal dimension of the panel and funnel is reduced so that it becomes difficult to use the existing facilities and parts of the cathode ray tube (such as a frame of the mask assembly, a spring for suspending the mask assembly to the interior of the panel, etc.) therefore, and there is a need for a new investment (related to the facility and the mold). This results in increased production cost.
Above all, when the panel and the funnel are thickened, the weight of the cathode ray tube is increased, thereby incurring the difficulty in handling.